Piston ignition points?

[Niels Abildgaard]

A combined power and heat plant and a powered para plane opposed piston engine will both benefit from spark plugs in center of pistons.
Has this been solved before and by whom?

 

[GreenTwin]

Fairbanks Morse 38D.
Submarine engine.

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[GreenTwin]

Looks like Junkers make one also.
.

 

[Niels Abildgaard]

Looks like Junkers make one also.
.

And also years before the given red neck, anglo saxon copies
The shown examples were diesels and never needed spark plugs in pistons.

 

[JimSvarv]

https://www.pattakon.com/pattakonFly.htm
This guy has a bunch of different 2 stroke designs.
Haven't seen one fly though.

If a opposed 2 stroke is built like 2 normal ones then I don't see how it wouldn't work like a normal one if that makes sense...
So maybe a good starting point for you?

If it's a uniflow design as your cutaway shows then your need either a blower for scavenging or connect the 2 crankcases to the intake port.
Maybe a stepped piston could be used to get more volume in one case.
But then you don't have petroil lubrication in the other crankcase...

While on a normal 2 stroke you would need 2 exhaust pipes, however some what smaller.

A strongh and light couple will also be needed between the cranks for a flying machine, maybe the only disadvantage of the opposite piston design for your application.
Beside that I don't see any problem with your idea.